Question

1. luis is investigating the structure of dna for a science - fair project. he learns that the building blocks of dna fit together in certain ways. building block a only fits with t and c only fits with g. he draws the sketch below to show what he has learned. luis wants to make a model of dna from his sketch. which of the following is the best choice to represent the building blocks of dna in his model? a. square toy blocks b. a sample of real dna c. a diagram that shows where dna is located in cells d. cardboard cut - outs that fit together like puzzle pieces 24. michael and paola wanted to investigate the flow of energy through the organisms in the ecosystem where they live, so they studied what certain organisms eat. the results of the investigation show that mice eat seeds produced by plants, and that a bird eats the mice. they want to make a model that is useful in relating their results. what should their model include? a. all of the animals in the ecosystem b. all of the possible food sources in the ecosystem c. the animals they studied and the foods those animals eat d. the animals they studied and the daily activities of those animals 25. victoria discovers a footprint of an organism that has been preserved in rock. through her investigations, she learns that sometimes when footprints are made in soft mud, they could be covered by sand. when the mud and sand become rock, the process preserves the footprint. which is the best model for victoria to choose to relate what she learned? a. a tray of sand with footprints in it b. a graph showing the composition of the mud and sand c. a footprint in clay that has been filled with plaster that has been allowed to harden d. a diorama that shows what earth looked like when the organism that made the footprint was alive

Explanation:

1. For the DNA - building - blocks model question, cardboard cut - outs that fit together like puzzle pieces can best represent the specific pairing of DNA building blocks (A - T and C - G). Square toy blocks don't show the specific pairing, a sample of real DNA is not a model for showing the building - block concept, and a diagram showing DNA location in cells is not relevant to building - block representation.
2. For the energy - flow in the ecosystem model question, since Michael and Paola studied what certain organisms eat (mice eat seeds, bird eats mice), the model should include the animals they studied and the foods those animals eat. Including all animals or all possible food sources is too broad, and including daily activities is not related to their study of energy - flow through eating.
3. For the footprint preservation model question, a footprint in clay that has been filled with plaster that has been allowed to harden can mimic the process of a footprint in soft mud being covered and preserved as rock. A tray of sand with footprints is just a simple footprint without the preservation aspect like rock - formation, a graph of mud and sand composition is not related to footprint preservation, and a diorama showing Earth's appearance when the organism was alive is not related to the footprint - preservation process.

Answer:

1. D. cardboard cut - outs that fit together like puzzle pieces
2. C. the animals they studied and the foods those animals eat
3. C. a footprint in clay that has been filled with plaster that has been allowed to harden